Currently, the device for detecting a rotation angle is applied to various industries, especially for detecting a motor rotation angle, industrial knob position, and vehicle steering wheel rotation angle in the automobile industry. However, the existing technical solutions still have the following defects. In one case, a process for detecting a rotation angle of an object capable of rotating more than 360 degrees was disclosed as in Patent No. CN1090315C. This solution is realized by a relative relation between two driven gears externally meshed with the main gear respectively and their respective rotation angles. Errors of the two driven gears are introduced to the calculation during the calculating process, so the fluctuation of precision, resolution, zero drift and nonlinearity of the rotation angle may be serious when analyzed from the performance perspective. Since the algorithms are complex, the system stability depends not only on the sensor but also on the stability of other units such as digital-to-analog converters, and accumulator inside micro control unit. In addition, certain requirements on the application environment are proposed for end users. Thus, the probability of occurrence of errors is relative high. In a second case, two pulse signals are output by using the principle of optoelectronics or the Hall principle, and the rotation angle is obtained from the pulse phase relation. For such a device and a detection process, the zero position cannot be marked and recorded from the output signals, and the user needs to identify the zero position again each time when the device is powered on. In addition, the resolution of the detection device depends on the rotation angle corresponding to a single pulse period, the numbers of the pulses should be distributed equally within 360 degrees, and the number of the hole or tooth corresponding to each pulse is limited within 360 degrees. Due to the facts that the space for installation is small and the size is limited, the highest resolution of the detection device may only reach up to 0.5 degrees. When the rotation angle is smaller than the resolution, no effective angle is output. Further, the rotation direction is determined by the sequence of the two pulses, so the rotation direction cannot be identified. Such angle detection device is likely to miss signal pulse. Consequently, no valid rotation angle is output.